Just a few questions on Rex.

His card says he has Dual DC-17 Hand Blasters. Does this mean he only uses 3 red dice or 6 red dice, 3 for each blaster?

For Fire Support can Rex participate in Fire Support using his (Call Me Captain) card if the range is 3. His card says his blasters have a range of 2.

His ranged attack is 3 Red. The Dual part is represented by Gunslinger, which allows him to attack two different targets, each with 3 Red.

To use Fire Support, the defender needs to be within range of at least one of the ranged weapons available to the unit with Fire Support. Since Rex's pistols are only maximum range 2, he can only use Fire Support against defenders that are within range 2.